The present invention relates generally to roller clamps for regulating the flow rate of a liquid through large bore plastic tubing.
Roller clamps are well-known devices for controlling the flow of liquid through plastic tubing, such as used in intravenous administration sets and other medical applications. Roller clamps have heretofore generally included an elongated frame, a movable roller disposed within the frame, and tubing extending through the frame. The flow of liquid through the tubing is regulated by moving the roller along an inclined path over the tubing within the frame. Movement of the roller selectively compresses or releases the tubing, thereby varying the flow path so as to attain a selected flow rate.
The use of roller clamps to regulate the flow of liquid through tubing is well known and has been particularly useful in controlling the flow of medical or medically-related liquids during surgical or post-operative procedures. Manufacturers of these clamps include Baxter Healthcare Corporation of Deerfield, Ill., and numerous others. Although roller clamps previously manufactured have generally worked satisfactorily, they suffer from certain drawbacks when applied to flow control in large bore plastic tubing, where high flow rates are necessary.
Large bore tubing, as used here, means tubing having an inside diameter of at least about 0.19 inches (4.83 mm) and a wall thickness of at least about 0.04 inches (1.02 mm). For example, in a transuretheralresectomy (TUR), a flow rate of up to 1000 ml/hr of sterile water is required as part of the procedure, thus requiring large bore tubing for directing the flow of water from the source container to the procedure site or instrument.
Roller clamps of existing design have displayed a number of deficiencies in such applications. One such difficulty is in accurate and/or lack of sustained fluid flow rate control including the inability to maintain a complete shut-off position over a lengthy period of time, e.g., twenty-four hours. Another problem often encountered is roller clamp breakage or roller "pop-out," which occurs when the roller comes out of the frame or disengages from roller tracks in which it moves.
These difficulties are believed to be particularly acute in large bore tubing applications because of high stress imposed on the roller clamp in such applications. In the full shut-off position, in particular, the stress imposed on roller clamp assembly is especially high, and undue flexibility in the roller clamp frame is believed to have resulted in one or more of the above-described drawbacks.
Accordingly, it is a general object of the present invention to provide a large bore tubing roller clamp assembly which does not suffer from the drawbacks described above.
It is a more specific object of the present invention to provide a large bore tubing roller clamp assembly which can withstand the stress imposed while providing reliable flow control rates, including complete and sustained shutoff capability.